CN115297951B

CN115297951B - Membrane cleaning device, membrane separation activated sludge system and membrane cleaning method

Info

Publication number: CN115297951B
Application number: CN202080098628.3A
Authority: CN
Inventors: 林佳史; 今村英二; 野田清治
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2023-02-28
Anticipated expiration: 2040-03-24
Also published as: CN115297951A; JP6887574B1; JPWO2021191997A1; WO2021191997A1

Abstract

A membrane cleaning device (40) is provided with an ozone gas supply unit (10), a dissolved water supply unit (8), an ozone water supply unit (11), and a control unit (12), wherein the ozone gas supply unit (10) supplies ozone gas to an ozone water generation unit (9), the dissolved water supply unit (8) supplies dissolved water to the ozone water generation unit (9), the ozone water supply unit (11) supplies ozone water stored in the ozone water generation unit (9) to a separation membrane (2), and the control unit (12) controls: in a state where the ozone gas supply part (10) is caused to supply ozone gas from the ozone gas supply part (10) to the ozone water generation part (9), the dissolved water supply part (8) is caused to supply dissolved water from the dissolved water supply part (8) to the ozone water generation part (9), and the ozone water supply part (11) is caused to supply ozone water from the ozone water generation part (9) to the separation membrane (2).

Description

Membrane cleaning device, membrane separation activated sludge system and membrane cleaning method

Technical Field

The invention relates to a membrane cleaning device, a membrane separation activated sludge system and a membrane cleaning method.

Background

In a Membrane separation activated sludge process, which is a wastewater treatment method using an MBR (Membrane Bio Reactor: membrane separation activated sludge apparatus), wastewater is reacted with microorganisms, and the resulting fouling substances are removed as sludge. The contaminated substances generated are removed from the wastewater by solid-liquid separation using a separation membrane. The separation membrane filters and separates the contaminants contained in the wastewater, but the contaminants may adhere to the surface and the pores and clog the pores due to continuous use. The separation membrane clogged is deteriorated in filtration performance, i.e., solid-liquid separation performance. Therefore, conventionally, there has been proposed a cleaning method called "backwashing" in which cleaning water containing an oxidizing agent such as ozone is injected in a direction opposite to the filtration direction to clean the separation membrane. In a conventional membrane cleaning apparatus, ozone gas is dissolved in dissolved water in a semi-batch manner (japanese: semi-cyclic) to generate ozone water. That is, the dissolved water is supplied to an ozone water generating part capable of storing the dissolved water, and after the supply of the dissolved water is stopped at a time when the predetermined amount is reached, ozone gas is continuously supplied to the dissolved water held at the predetermined amount, thereby generating ozone water from the dissolved water. When the separation membrane is cleaned by supplying the ozone water generated in the ozone water generation unit, the supply of ozone gas is continued with the supply of the dissolved water to the ozone water generation unit stopped, in order to maintain the dissolved ozone concentration of the ozone water (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6430091

Disclosure of Invention

Problems to be solved by the invention

However, in the membrane cleaning apparatus as described above, the amount of water in the ozone water generation unit decreases during the cleaning process of the separation membrane, and the water level of the ozone water in the ozone water generation unit decreases. Here, the ozone gas in the ozone water supplied to the ozone water generating part rises toward the water surface, and therefore, when the water level of the ozone water is low, the contact time of the gas and the liquid is shortened, and there is a problem that the dissolution efficiency of the ozone gas is lowered.

The present application discloses a technique for solving the above-described problems, and aims to provide a membrane cleaning apparatus, a membrane separation activated sludge system, and a membrane cleaning method that can prevent a decrease in the dissolution efficiency of ozone gas.

Means for solving the problems

The membrane cleaning device disclosed in the present application cleans a separation membrane, which separates a contaminated substance contained in water to be treated from the water to be treated, by ozone water stored in an ozone water generation unit, and includes: an ozone gas supply unit for supplying ozone gas to the ozone water generation unit; a dissolved water supply unit for supplying dissolved water to the ozone water generation unit, using water introduced from the outside or treated water treated by the separation membrane as dissolved water; an ozone water supply part which supplies the ozone water stored in the ozone water generation part to the separation membrane; and a control unit that performs control such that: the control unit includes an ozone concentration acquisition unit that acquires a dissolved ozone concentration of the ozone water, a storage unit that stores a predetermined 1 st threshold value and a predetermined 2 nd threshold value, and a determination unit that determines whether or not the dissolved water and the ozone water can be transferred, wherein the determination unit determines that the dissolved water and the ozone water can be transferred, and the ozone gas supply unit is in a state in which the ozone gas is supplied from the ozone gas supply unit to the ozone water generation unit, the method comprises supplying the dissolved water from the dissolved water supply unit to the ozone water generation unit, supplying the ozone water from the ozone water generation unit to the separation membrane, stopping the supply of the dissolved water from the dissolved water supply unit to the ozone water generation unit, stopping the supply of the ozone water from the ozone water generation unit to the separation membrane, and determining whether or not the dissolved ozone concentration is equal to or higher than a predetermined 1 st threshold value in the step of generating the ozone water by supplying the ozone gas from the ozone water supply unit to the ozone water generation unit in a state where the supply of the dissolved water from the dissolved water supply unit to the ozone water generation unit and the supply of the ozone water from the ozone water generation unit to the separation membrane are stopped, when the dissolved ozone concentration is less than a predetermined 2 nd threshold value, in the step of causing the ozone gas supply unit to supply ozone gas from the ozone gas supply unit to the ozone water generation unit, causing the dissolved water supply unit to supply dissolved water from the dissolved water supply unit to the ozone water generation unit, and causing the ozone water transfer unit to transfer ozone water from the ozone water generation unit to the separation membrane, the determination unit determines whether or not the dissolved ozone concentration is less than a predetermined 2 nd threshold.

In addition, the membrane cleaning method disclosed in the present application cleans a separation membrane that separates contaminated substances contained in water to be treated from the water to be treated by ozone water stored in an ozone water generation unit, and includes an ozone gas supply step of supplying ozone gas to the ozone water generation unit in a state where supply of the water to be dissolved to the ozone water generation unit is stopped and ozone water transfer from the ozone water generation unit to the separation membrane is stopped, a dissolved water supply step of supplying the water to be dissolved to the ozone water generation unit, an ozone water transfer step of performing the dissolved water supply step and the ozone water transfer step while supplying ozone gas to the separation membrane, in the ozone water transfer step, water introduced from the outside or treated water treated by the separation membrane is supplied to the ozone water generation unit as dissolved water, and the ozone water supply step is performed, and the ozone water transfer step is performed in the continuous operation step, and when ozone gas supply to the ozone water generation unit reaches or more than a first predetermined ozone water transfer threshold value in the ozone water supply step, the ozone water supply step is performed, and the ozone water transfer step is switched to the ozone water transfer step to be performed in a state where the dissolved water supply step is performed.

Effects of the invention

With the film cleaning apparatus and the film cleaning method disclosed in the present application, it is possible to prevent a decrease in the dissolution efficiency of ozone gas.

Drawings

Fig. 1A is a configuration diagram showing a membrane separation activated sludge system and a membrane cleaning apparatus in embodiment 1, and is a diagram for explaining a dissolved water supply step.

Fig. 1B is a diagram showing the configuration of the membrane separation activated sludge system and the membrane cleaning apparatus in embodiment 1, and is a diagram for explaining the ozone gas supply step.

Fig. 1C is a diagram showing the configuration of the membrane separation activated sludge system and the membrane cleaning apparatus in embodiment 1, and is a diagram illustrating a continuous operation step.

Fig. 2 is a diagram showing a configuration example of the control unit according to embodiment 1.

Fig. 3 is a flowchart showing the operation of the membrane cleaning apparatus according to embodiment 1.

Fig. 4A is a diagram showing the configuration of the membrane separation activated sludge system and the membrane cleaning apparatus in embodiment 2, and is a diagram for explaining the ozone gas supply step.

Fig. 4B is a diagram showing the configuration of the membrane separation activated sludge system and the membrane cleaning apparatus in embodiment 2, and is a diagram illustrating a continuous operation step.

Fig. 5 is a diagram showing an example of the hardware configuration of the control unit according to embodiment 1.

Detailed Description

Hereinafter, embodiments of the membrane separation activated sludge system and the membrane cleaning apparatus disclosed in the present application will be described in detail with reference to the drawings. The embodiments described below are examples.

Embodiment mode 1

Embodiment 1 is described with reference to fig. 1A to 3. Fig. 1A to 1C are structural diagrams showing a membrane separation activated sludge system and a membrane cleaning apparatus in embodiment 1, fig. 1A is a diagram illustrating a dissolved water supply step, fig. 1B is a diagram illustrating an ozone gas supply step, and fig. 1C is a diagram illustrating a continuous operation step. In addition, when each pipe is indicated by an arrow, the fluid flowing through the pipe is shown to flow in the direction of the arrow. When no arrow is indicated, no fluid flows in the process. As shown in fig. 1A, the membrane separation activated sludge system 100 includes a membrane separation activated sludge apparatus 20 and a membrane cleaning apparatus 40, the membrane separation activated sludge apparatus 20 includes a membrane separation tank 1 and a separation membrane 2, and the membrane cleaning apparatus 40 cleans the separation membrane 2. An inflow pipe 5 as a pipe member through which wastewater or the like flows is connected to the membrane separation tank 1, and wastewater or the like flows into the membrane separation tank 1 through the inflow pipe 5. The wastewater or the like flowing into the membrane separation tank 1 is stored in the membrane separation tank 1 as the water to be treated 6.

The side surfaces and the bottom surface of the membrane separation tank 1 are made of concrete, and water leakage in the membrane separation tank 1 is prevented. The water to be treated 6 stored in the membrane separation tank 1 contains not only the contaminants but also microorganisms (hereinafter referred to as activated sludge) capable of capturing the contaminants. Therefore, the contaminated substances in the water to be treated 6 are contained in the water to be treated 6 in a state of being captured in the activated sludge.

The separation membrane 2 is a rectangular parallelepiped membrane member having each surface formed of a membrane such as a hollow fiber membrane, for example, and the direction from the outside to the inside of a rectangular parallelepiped space partitioned by the surfaces is the filtration direction of the separation membrane 2. The separation membrane 2 is disposed in the membrane separation tank 1 and immersed in the water to be treated 6. Further, one end of a filtered water pipe 3a is inserted inside the separation membrane 2. The filtered water pipe 3a is a pipe member for discharging the water to be treated 6 filtered by the separation membrane 2 to the outside of the system as treated water 7, and is provided with a filter pump 4 for sucking the treated water 7 by pressure. By operating the filtration pump 4, the treated water 7 inside the separation membrane 2 flows into the filtered water pipe 3a, and the treated water 6 outside the separation membrane 2 flows into the separation membrane 2. At this time, the water 6 to be treated flowing through the separation membrane 2 is filtered, and the activated sludge in the water 6 to be treated is separated by the separation membrane 2. Since the activated sludge captures the contaminants in the water 6 to be treated as described above, the contaminants contained in the water 6 to be treated are also separated by separating the activated sludge in the water 6 to be treated. The activated sludge and the contaminated substances separated from the water 6 to be treated adhere to the separation membrane 2. The water to be treated 6 from which the contaminants have been removed in this way becomes treated water 7, which is sucked by the filter pump 4 as described above, flows through the filtered water pipe 3a, and is discharged from the other end of the filtered water pipe 3a to the outside of the system. The membrane constituting the separation membrane 2 is not limited to the hollow fiber membrane described above, and a flat membrane or the like may be used. The separation membrane 2 may be a membrane member capable of separating solids and liquids in the water 6 to be treated containing activated sludge, and therefore, an ultrafiltration membrane (UF), a microfiltration Membrane (MF), or the like may be used as the separation membrane 2.

When the separation of the solid and the liquid in the water 6 to be treated is continued by the separation membrane 2, in other words, when the filtration treatment for filtering the water 6 to be treated located outside the separation membrane 2 is continued, activated sludge and contaminants in the water 6 to be treated may adhere to the surface of the separation membrane 2 or the pores of the separation membrane 2 and clog the same. If clogging occurs, the filtration rate by the separation membrane 2 may decrease, which may decrease the treatment rate of the water to be treated 6. Thus, there is a possibility that the water treatment efficiency of the membrane separation activated sludge system 100 is lowered by continuing to use the separation membrane 2. Therefore, it is necessary to appropriately clean the separation membrane 2 to prevent clogging and the like.

The membrane cleaning device 40 is a cleaning device for cleaning the separation membrane 2. The membrane cleaning device 40 includes: a dissolved water supply unit 8 for supplying dissolved water to the ozone water generation unit 9; an ozone water generator 9 for generating ozone water by dissolving ozone gas in water to be dissolved; an ozone gas supply unit 10 for supplying ozone gas to the ozone water generation unit 9; an ozone water supply part 11 for injecting the ozone water generated by the ozone water generation part 9 into the inside of the separation membrane 2; and a control unit 12 for controlling the operations of the dissolved water supply unit 8, the ozone gas supply unit 10, and the ozonated water supply unit 11 according to the process. The dissolved water supply unit 8, the ozone gas supply unit 10, the ozonated water feed unit 11, and the control unit 12 are connected to each other via

signal lines

50a, 50b, and 50c, respectively. In fig. 1A to 1C, arrows on the signal lines 50a to 50C indicate that the control unit 12 operates the target functional unit in the steps shown in the respective drawings. For example, in the dissolved water supply step shown in fig. 1A, the dissolved water supply unit 8 is operated, but the ozone gas supply unit 10 and the ozonated water feed unit 11 are stopped. The controller 12 is connected to a concentration measuring unit, which is the dissolved ozone sensor 9b of the ozone water generator 9, via a signal line 51.

The dissolved water supply unit 8 is connected to the ozone water generation unit 9 via the dissolved water supply pipe 3 c. The dissolved water is dissolved by the ozone gas in the ozone water generating part 9 to become ozone water, and the dissolved water is supplied from the dissolved water supplying part 8 to the ozone water generating part 9 through the dissolved water supply pipe 3 c. The dissolved water supply unit 8 starts or stops supplying the dissolved water to the ozone water generation unit 9 in response to a control signal from the control unit 12. The water to be dissolved is not particularly limited, and for example, tap water or industrial water, or treated water 7 filtered by the separation membrane 2 can be used. When the treated water 7 is used as the water to be dissolved, a pipe for transporting the treated water 7 from the filtered water pipe 3a to the dissolved water supply unit 8 and a pump for transporting the treated water 7 are necessary, but it is not necessary to newly introduce water from the outside, and therefore the cost required for cleaning can be reduced.

The ozonated water generator 9 is connected to an ozonated water feed unit 11 via an ozonated water feed pipe 3b 1. The ozone water generator 9 is configured to be capable of storing liquid therein, and capable of storing the dissolved water supplied from the dissolved water supplier 8 and the ozone water generated from the dissolved water. A gas diffusion portion 9a connected to the ozone gas supply portion 10 via an ozone gas supply pipe 3d is provided at the bottom of the ozone water generation portion 9. The ozone gas supplied from the ozone gas supply unit 10 is discharged as bubbles from the gas diffusion unit 9a, and injected into the dissolved water in the ozone water generation unit 9. A connection portion (not shown) between the ozone water generator 9 and the dissolved water supply pipe 3c is provided on one side wall of the ozone water generator 9, and a connection portion (not shown) between the ozone water generator 9 and the ozone water supply pipe 3b1 is provided on the other side wall of the ozone water generator 9. The connection between the ozone water generator 9 and the dissolved water supply pipe 3c is provided at a position higher than the connection between the ozone water generator 9 and the ozone water supply pipe 3b 1. Further, an ozone off-gas pipe 3e communicating with the outside of the ozone water generating part 9 is provided above the ozone water generating part 9. The ozone off-gas pipe 3e discharges the ozone gas that is not dissolved in the ozone water generating unit 9 to the outside of the system as an ozone off-gas.

The position of the gas diffusion part 9a is not limited to the bottom of the ozone water generation part 9, but it is preferable to provide the gas diffusion part 9a as downward as possible because bubbles of ozone gas discharged from the gas diffusion part 9a flow upward toward the water surface of the water to be dissolved. By providing the gas diffusion portion 9a at the lower side, the contact time of the water to be dissolved and the ozone gas is prolonged, and the dissolution efficiency can be improved. The position of the connection between the ozone water generator 9 and the dissolved water supply pipe 3c and the position of the connection between the ozone water generator 9 and the ozone water supply pipe 3b1 are not particularly limited, but it is preferable to make the distance between them as large as possible. Further, by providing the connection portion with the dissolved water supply pipe 3c at a position higher than the connection portion with the ozone water delivery pipe 3b1 as described above, the dissolution efficiency of ozone gas can be improved. In this case, since the water to be dissolved flows in from a high position, the water flow of the water to be dissolved becomes a downward flow, and the water flow of the water to be dissolved and the gas flow of the ozone gas become a convection flow. In this case, the water to be dissolved and the ozone gas are in convective contact with each other, and the dissolution efficiency is improved.

The ozone water generating unit 9 is provided with a dissolved ozone sensor 9b. The dissolved ozone sensor 9b continuously or intermittently measures the dissolved ozone concentration of the ozonated water (including the case where the dissolved water is mixed, the same applies hereinafter) in the ozonated water generation unit 9, and transmits the measurement result to the control unit 12 via the signal line 51.

The ozone water generator 9 is not particularly limited as long as it has a structure capable of generating ozone water by dissolving ozone gas in water to be dissolved. The ozone water generating unit 9 of embodiment 1 is provided as an ozone water generating unit capable of storing dissolved water and having both a function of storing dissolved water and a function of dissolving ozone gas in dissolved water, but a storage tank for storing dissolved water and a dissolving mechanism for dissolving ozone gas in dissolved water stored in the storage tank may be separated. As a method for dissolving ozone gas in the water to be dissolved, in addition to a method (air diffusing type) of providing the air diffusing portion 9a in the ozone water generating portion 9, an ozone gas dissolving method such as a jet type or a dissolving film type can be used.

The ozone gas supply section 10 supplies ozone gas to the gas diffusion section 9a in the ozone water generation section 9 through the ozone gas supply pipe 3 d. The ozone gas supply section 10 starts or stops the supply of ozone gas to the ozone water generation section 9 in accordance with a control signal from the control section 12. The ozone gas supply portion 10 is composed of a raw material gas supply portion (not shown) and an ozone gas generator (not shown) that generates ozone gas using oxygen supplied from the raw material gas supply portion as a raw material. As the raw material gas generating unit, for example, a liquid oxygen cylinder or an oxygen generating apparatus using VPSA (Vacuum Pressure Swing Adsorption) is used, but there is no particular limitation as long as it is an apparatus capable of supplying oxygen. As the ozone gas generator, for example, a discharge type ozone gas generator can be used.

Further, a pH adjusting means may be provided in the dissolved water supply unit 8 or the ozone water generation unit 9 to adjust the pH of the ozone water, the dissolved water, or both from 2 to 6. Since the lower the pH value, the less likely the self-decomposition of ozone occurs, the ozone water can be efficiently generated by adjusting the pH value of the water to be dissolved as described above while suppressing the self-decomposition of ozone. The same effect is obtained when the pH of the ozone water is adjusted. In the above case, the amount of the required ozone gas can be reduced, and therefore the cost required for cleaning can be reduced. Further, the temperature adjusting means may be provided in the dissolved water supply unit 8, the ozonated water generation unit 9, or both, to adjust the temperatures of the ozonated water and the dissolved water to be constant or lower. Since the solubility of ozone increases as the water temperature decreases, by adjusting the water temperature to a constant value or less, ozone water having a higher concentration is generated, and the cleaning effect by ozone water is improved. In this case, the required amount of dissolved water can be reduced, and therefore the cost required for cleaning can be reduced.

The ozonated water supply unit 11 is connected to the ozonated water generation unit 9 via an ozonated water supply pipe 3b1, and is connected to the filtered water pipe 3a via an ozonated water supply pipe 3b 2. The ozonated water feed unit 11 feeds the ozonated water generated in the ozonated water generation unit 9 from the ozonated water generation unit 9, and injects the ozonated water into the inside of the separation membrane 2 through the filtration pipe 3 a. When the ozone water is supplied to the inside of the separation membrane 2 by the ozone water supply part 11, the ozone water flows from the inside to the outside (the direction opposite to the filtration direction) of the separation membrane 2, and the back washing of the separation membrane 2 is performed. As a result, the contaminated substances and sludge adhering to the separation membrane 2 are separated from the separation membrane 2, and the separation membrane 2 is cleaned. The ozonated water feed unit 11 starts or stops the ozonated water feed to the separation membrane 2 in accordance with a control signal from the control unit 12.

The controller 12 sends control signals to the dissolved water supplier 8, the ozone gas supplier 10, and the ozonated water feeder 11, and performs control for switching the processes to be performed. That is, the control signal of the control unit 12 has a function as a switching signal for switching the process to be performed. The steps performed in embodiment 1 include a "dissolved water supply step", an "ozone gas supply step", an "ozone water supply step", and a "continuous operation step". The "dissolved water supply step" is a step of supplying the dissolved water from the dissolved water supply unit 8 to the ozonated water generation unit 9. As shown in fig. 1A, in the dissolved water supply step, the dissolved water supply unit 8 operates in response to a control signal from the controller 12, and the dissolved water flows from the dissolved water supply unit 8 to the ozonated water generation unit 9 in the dissolved water supply pipe 3 c. On the other hand, since the ozone gas supply part 10 is stopped, no ozone gas flows through the ozone gas supply pipe 3d, and no ozone off-gas is discharged from the ozone off-gas pipe 3e. Further, the ozonated water feed unit 11 is also stopped, and therefore, no ozonated water flows in the ozonated water feed pipes 3b1 and 3b 2. In the dissolved water supply step, the water 6 to be treated can be treated by the membrane separation activated sludge device 20 in parallel. In FIG. 1A, there is shown: the water to be treated 6 flows through the inflow pipe 5 and flows into the membrane separation tank 1, and the treated water 7 sucked by the filtration pump 4 flows through the filtered water pipe 3a and is discharged to the outside of the system.

The "ozone gas supply step" is a step of generating ozone water in a semi-batch manner by continuously supplying ozone gas to the water containing a predetermined amount of dissolved water. As shown in fig. 1B, in the ozone gas supply step, the ozone gas supply portion 10 is operated in response to a control signal from the control portion 12, and ozone gas flows from the ozone gas supply portion 10 into the ozone water generation portion 9 through the ozone gas supply pipe 3 d. Further, the ozone off-gas is discharged from the ozone off-gas pipe 3e. On the other hand, since the supply unit 8 for the dissolved water is stopped, the dissolved water does not flow in the dissolved water supply pipe 3 c. Further, the ozonated water supply section 11 is also stopped, and therefore, no flow of ozonated water is present in the ozonated water supply pipes 3b1 and 3b 2. In the ozone gas supply step, the water 6 to be treated can be treated by the membrane separation activated sludge device 20 in parallel as in the dissolved water supply step.

The "ozone water supply step" is a step of supplying the ozone water stored in the ozone water generator 9 to the separation membrane 2 to clean the separation membrane 2. The "continuous operation step" is a step of: ozone water is generated in a continuous manner by supplying the dissolved water from the dissolved water supply unit 8 to the ozone water generation unit 9 and supplying the ozone water from the ozone water supply unit 10 to the separation membrane 2 while supplying the ozone gas from the ozone water generation unit 9; then, the separation membrane 2 is cleaned by supplying ozone water to the separation membrane 2. In other words, in the continuous operation step, while ozone water is supplied from the ozone water generator 9 to the separation membrane 2, new dissolved water is supplied to the ozone water generator 9, and the following steps are performed in parallel: cleaning the separation membrane 2 by ozone water; and generating ozone water by a continuous manner. That is, the "continuous operation step" in embodiment 1 is a step of performing the dissolved water supply step and the ozone water supply step while supplying ozone gas to the ozone water generation unit 9. As shown in fig. 1C, in the continuous operation step, the dissolved water supply unit 8, the ozone gas supply unit 10, and the ozonated water feed unit 11 operate in accordance with a control signal from the control unit 12. Thereby, the dissolved water flows from the dissolved water supply portion 8 into the ozone water generation portion 9 in the dissolved water supply pipe 3c, and the ozone gas flows from the ozone gas supply portion 10 into the ozone water generation portion 9 in the ozone gas supply pipe 3 d. Further, the ozone off-gas is discharged from the ozone off-gas pipe 3e. Further, the ozonated water flows from the ozonated water generation unit 9 to the ozonated water feed unit 11 in the ozonated water feed pipe 3b1, and the ozonated water flows from the ozonated water feed unit 11 to the filtered water pipe 3a in the ozonated water feed pipe 3b 2. The ozone water flowing through the filtered water pipe 3a flows into the inside of the separation membrane 2, and the back washing of the separation membrane 2 is performed as described above. In addition, in the continuous operation step, since it is necessary to flow ozone water to the separation membrane 2 through the filtered water pipe 3a, the water 6 to be treated is not treated by the membrane separation activated sludge device 20.

A specific configuration of the control unit 12 will be described. Fig. 2 is a diagram showing a configuration example of a control unit according to embodiment 1. The control unit 12 includes an ozone concentration receiving unit 13, a storage unit 14, a determination unit 15, and a control signal transmission unit 16. The ozone concentration receiving unit 13 and the determination unit 15 are connected via a signal line 52 a. The storage unit 14 and the determination unit 15 are connected via a signal line 52 b. The determination unit 15 and the control signal transmission unit 16 are connected via a signal line 52 c. The ozone concentration receiving unit 13 is connected to the dissolved ozone sensor 9b via a signal line 51, and receives data of the dissolved ozone concentration as a measurement result of the dissolved ozone sensor 9b via the signal line 51. The ozone concentration receiving unit 13 transmits the received data of the dissolved ozone concentration to the determination unit 15 via the signal line 52 a. The storage unit 14 stores the dissolved ozone concentration that becomes a predetermined threshold value. The threshold value stored in the storage unit 14 is a threshold value for determining whether or not the continuous operation process can be switched. The ozone concentration receiving unit 13 corresponds to an ozone concentration acquiring unit.

The determination unit 15 determines the process to be performed by the membrane cleaning device 40. The determination unit 15 acquires data of the measured value of the dissolved ozone concentration of the ozone water in the ozone water generation unit 9 from the ozone concentration reception unit 13, and compares the measured value of the dissolved ozone concentration with the threshold stored in the storage unit 14. When the measured value of the dissolved ozone concentration is equal to or higher than the threshold value, the step to be performed is determined as the continuous operation step. When the measured value of the dissolved ozone concentration is less than the threshold value, the process to be performed is determined as an ozone gas supply process. In this way, the determination unit 15 determines whether or not the process to be performed can be switched between the ozone gas supply process and the continuous operation process based on the dissolved ozone concentration of the ozone water in the ozone water generation unit 9.

When the determined process is different from the process being performed, the determination unit 15 generates a control signal for switching the process to be performed, and transmits the generated control signal to the control signal transmission unit 16 via the signal line 52 c. The control signal transmitter 16 transmits the control signal received from the decision unit 15 to the dissolved water supplier 8, the ozone gas supplier 10, and the ozonated water feeder 11 via the

signal lines

50a, 50b, and 50c, respectively.

For example, when switching from the ozone gas supply step to the continuous operation step, a control signal for starting water supply is generated as a control signal to the dissolved water supply unit 8, and a control signal for starting water supply is generated as a control signal to the ozonated water supply unit 11. Before and after the switching of the process, the operation of the ozone gas supply unit 10 is not changed (the supply of ozone gas is continued), and therefore, in this case, a control signal to the ozone gas supply unit 10 is not generated.

Fig. 5 is a diagram showing an example of a hardware configuration for realizing the control unit 12. The processor 71 executes a program stored in the memory 72 or the hard disk 73, thereby realizing each functional unit of the control unit 12 described above. Further, the functions of the control unit 12 may be realized by the cooperation of the plurality of processors 71 and the plurality of memories 72 or hard disks 73. The control unit 12 further includes a receiving circuit 74, and receives data from the dissolved ozone sensor 9b via the receiving circuit 74. The data of the dissolved ozone concentration received from the dissolved ozone sensor 9b, the result of the calculation performed by the processor 71, and the predetermined threshold value are stored in the memory 72 or the hard disk 73. The control unit 12 is provided with a transmission circuit 75, and transmits control signals to the dissolved water supply unit 8, the ozone gas supply unit 10, and the ozonated water feed unit 11 via the transmission circuit 75.

Next, the operation will be described. Fig. 3 is a flowchart showing the operation of the membrane cleaning apparatus according to embodiment 1. First, it is checked whether or not a predetermined amount of water to be dissolved is stored in the ozone water generating unit 9 (step ST 001). If a predetermined amount of dissolved water is stored in the ozonated water generator 9, the process proceeds to step ST003.

When a predetermined amount of the dissolved water is not stored in the ozonated water generation unit 9, the dissolved water is supplied to the ozonated water generation unit 9 (step ST002, dissolved water supply step). First, the controller 12 switches the process to be performed to the dissolved water supply process. Specifically, the controller 12 sends a water supply start control signal to the dissolved water supplier 8 to start water supply of the dissolved water. The dissolved water supplied from the dissolved water supply unit 8 flows through the dissolved water supply pipe 3c to the ozonated water generation unit 9, and the dissolved water is supplied to the ozonated water generation unit 9. After the supply of the dissolved water is started, step ST001 is periodically performed to check the dissolved water stored in the ozone water generating unit 9. When a predetermined amount of the dissolved water is stored in the ozone water generating unit 9, the process proceeds to step ST003.

When a predetermined amount of dissolved water is stored in the ozone water generating part 9, the supply of ozone gas from the ozone gas supplying part 10 to the ozone water generating part 9 is started in a state where the supply of dissolved water from the dissolved water supplying part 8 to the ozone water generating part 9 is stopped (step ST 003). Specifically, the controller 12 sends a control signal for stopping the water supply to the dissolved water supplier 8 to stop the water supply of the dissolved water. The control section 12 sends a control signal for starting the supply to the ozone gas supply section 10 to start the supply of the ozone gas. Thus, the process to be performed is switched to the ozone gas supply process, and the semi-batch production of ozone water is started. In addition, when the water supply of the dissolved water is not performed as in the case where the step ST002 is not performed, the operation of stopping the water supply is not necessary.

In the ozone gas supply step, ozone gas is dissolved in the dissolved water stored in the ozone water generating unit 9 to generate ozone water (step ST 004). The ozone gas supplied from the ozone gas supply part 10 flows through the ozone gas supply pipe 3d to the gas diffusion part 9a in the ozone water generation part 9, and bubbles of the ozone gas are injected into the water to be dissolved from the gas diffusion part 9a. The bubbles of the ozone gas flow from the gas diffusing portion 9a toward the water surface of the dissolved water above. The bubbles of the ozone gas come into contact with the water to be dissolved while the water to be dissolved flows upward, and are partially dissolved in the water to be dissolved. Undissolved ozone gas is discharged to the outside of the system through an ozone off-gas pipe 3e. Ozone water is produced by dissolving ozone gas in the dissolved water as described above. During the ozone gas supply step, the dissolved ozone concentration of the ozone water in the ozone water generation unit 9 is continuously or intermittently measured by the dissolved ozone sensor 9b, and the measurement result is sent to the controller 12.

At a predetermined timing during the execution of the ozone gas supply step, it is determined whether or not the dissolved ozone concentration of the produced ozone water is equal to or higher than a predetermined threshold value, and whether or not the step to be executed is to be switched from the ozone gas supply step to the continuous operation step is determined (step ST 005). The determination unit 15 of the control unit 12 compares the measured value of the dissolved ozone concentration of the ozone water in the ozone water generation unit 9 with the threshold value stored in the storage unit 14, and continues the ozone gas supply process when the measured value of the dissolved ozone concentration is less than the threshold value (step ST 006). Thereafter, step ST005 is periodically performed, and whether or not to switch the process to be performed is determined based on the result of comparison between the measured value of the dissolved ozone concentration and the threshold value.

When the measured value of the dissolved ozone concentration is equal to or higher than the threshold value, the supply of the dissolved water to the ozone water generation part 9 and the supply of the ozone water to the separation membrane 2 are started while continuing the supply of the ozone gas to the ozone water generation part 9 (step ST 007). Specifically, the controller 12 sends a control signal for starting water supply to the dissolved water supplier 8 and the ozonated water supply unit 11, respectively, and starts supplying the dissolved water from the dissolved water supplier 8 to the ozonated water generator 9 and supplying the ozonated water from the ozonated water generator 9 to the separation membrane 2. Thus, the step to be performed is switched from the ozone gas supply step to the continuous operation step, the cleaning of the separation membrane 2 with ozone water is started, and the generation of ozone water is switched from the semi-batch type to the continuous type. After the switching to the continuous operation step, the supply of ozone gas from the ozone gas supply unit 10 to the ozone water generation unit 9 is continued.

In the continuous operation step, while continuing to supply ozone gas to the ozonated water generation part 9, the dissolved water is supplied from the dissolved water supply part 8 to the ozonated water generation part 9, and ozonated water is supplied from the ozonated water generation part 9 to the separation membrane 2, whereby the separation membrane 2 is washed with ozonated water (step ST 008). The supply of the dissolved water is the same as in the dissolved water supply step of step ST 002. The ozone water is supplied from the ozone water supply part 11. First, the ozonated water in the ozonated water generator 9 is supplied from the ozonated water generator 9 to the ozonated water supply unit 11 through the ozonated water supply pipe 3b 1. Next, the ozonated water supplied to the ozonated water supply unit 11 is supplied to the ozonated water supply unit 3a via the ozonated water supply pipe 3b2, and ozonated water is injected into the inside of the separation membrane 2 from the ozonated water supply pipe 3 a. When ozone water is supplied to the inside of the separation membrane 2 as described above, ozone water flows from the inside to the outside (the direction opposite to the filtration direction) of the separation membrane 2, and the separation membrane 2 is cleaned by backwashing. In this way, the controller 12 in the process of performing the continuous operation step performs the dissolved water supply step by causing the dissolved water supply unit 8 to supply the dissolved water from the dissolved water supply unit 8 to the ozonated water generation unit 9 while causing the ozone gas supply unit 10 to supply the ozone gas from the ozone gas supply unit 10 to the ozonated water generation unit 9, and performs the ozonated water supply step by causing the ozonated water feed unit 11 to feed the ozonated water from the ozonated water generation unit 9 to the separation membrane 2. In addition, during the continuous operation process, the dissolved ozone sensor 9b continues to measure the concentration of dissolved ozone.

In the continuous operation process of embodiment 1, the supply of the dissolved water to the ozonated water generator 9 and the supply of ozonated water from the ozonated water generator 9 are performed, and therefore the water amount and water level in the ozonated water generator 9 are maintained by appropriately setting the supply amount of the dissolved water and the supply amount of the ozonated water. Further, since ozone gas is also supplied, the decrease in the dissolved ozone concentration is also suppressed.

At a predetermined timing during the execution of the continuous operation step, it is determined whether or not the dissolved ozone concentration of the ozone water in the ozone water generation unit 9 is less than a predetermined threshold value, and whether or not the step to be executed is to be switched from the continuous operation step to the ozone gas supply step is determined (step ST 009). The determination unit 15 of the control unit 12 compares the measured value of the dissolved ozone concentration of the ozonated water in the ozonated water generation unit 9 with the threshold value stored in the storage unit 14, and determines whether or not the cleaning of the separation membrane 2 is completed when the measured value of the dissolved ozone concentration is equal to or higher than the threshold value (step ST 011). When the cleaning is completed, the supply of ozone gas to the ozone water generation part 9, the supply of the dissolved water to the ozone water generation part 9, and the ozone water supply to the separation membrane 2 are stopped (step ST 013). Specifically, the control unit 12 sends a control signal for stopping the supply of the dissolved water to the dissolved water supply unit 8 and the ozonated water supply unit 11, respectively, and stops the supply of the dissolved water from the dissolved water supply unit 8 to the ozonated water generation unit 9 and the delivery of the ozonated water from the ozonated water generation unit 9 to the separation membrane 2, and the control unit 12 sends a control signal for stopping the supply to the ozone gas supply unit 10, and stops the supply of the ozone gas from the ozone gas supply unit 10 to the ozonated water generation unit 9. When the cleaning of the separation membrane 2 is not completed, the continuous operation process is continued (step ST 012). Thereafter, step ST009 is periodically performed, and it is determined whether or not to switch the process to be performed, based on the result of comparing the measured value of the dissolved ozone concentration with the threshold value.

When the measured value of the dissolved ozone concentration is less than the threshold value, the supply of the ozone gas to the ozone water generation unit 9 is continued while the supply of the dissolved water to the ozone water generation unit 9 and the ozone water supply to the separation membrane 2 are stopped (step ST 010). Specifically, the controller 12 sends a control signal for stopping the supply of the dissolved water to the dissolved water supplier 8 and the ozonated water supplier 11, respectively, and stops the supply of the dissolved water from the dissolved water supplier 8 to the ozonated water generator 9 and the supply of the ozonated water from the ozonated water generator 9 to the separation membrane 2. Thus, the process to be performed is switched from the continuous operation process to the ozone gas supply process, the cleaning of the separation membrane 2 is stopped, and the generation of ozone water is switched from the continuous process to the semi-batch process. Thereafter, the process returns to step ST004. In this way, the controller 12 controls the steps to be performed such that the continuous operation step is performed when the measured value of the dissolved ozone concentration of the ozonated water in the ozonated water generator 9 is equal to or higher than the threshold value, and the ozone gas supply step is performed when the measured value of the dissolved ozone concentration of the ozonated water in the ozonated water generator 9 is lower than the threshold value.

In addition, the order of step ST009 and step ST011 may be switched, that is, it may be determined that the cleaning is completed first in the continuous operation step and whether or not the switching to the ozone gas supply step is possible if the cleaning is not completed.

The threshold used in step ST005, that is, the threshold for determining whether or not to switch from the ozone gas supply step to the continuous operation step, may be the same value as or a different value from the threshold used in step ST009, that is, the threshold for determining whether or not to switch from the continuous operation step to the ozone gas supply step.

In embodiment 1, the reduction in the dissolution efficiency of ozone gas can be prevented. More specifically, the separation membrane is cleaned by a continuous operation step in which the dissolved water supply section is caused to supply the dissolved water from the dissolved water supply section to the ozone water generation section and the ozone water generation section is caused to transfer the ozone water from the ozone water generation section to the separation membrane, while the ozone gas supply section is caused to supply the ozone gas from the ozone gas supply section to the ozone water generation section. In the continuous operation step, the dissolved water is supplied from the dissolved water supply unit to the ozone water generation unit, and therefore, reduction in the amount of water and lowering of the water level in the ozone water generation unit due to the ozone water transfer and reduction in the gas-liquid contact time caused by the reduction are suppressed. Therefore, in the continuous ozone water generation in the continuous operation step, the ozone gas dissolution efficiency is prevented from decreasing. Further, since the ozone gas is also supplied from the ozone gas supply unit to the ozone water generation unit, even if the undissolved ozone gas is discharged as an ozone off gas to the outside of the system or the self-decomposition of ozone occurs, the amount of ozone gas in the ozone water generation unit is maintained. Further, since the amount of water in the ozone water generation part is maintained in the continuous operation step, it is not necessary to newly supply the dissolved water when the ozone gas supply step is performed again. Therefore, the time required for producing a predetermined amount of ozone water can be shortened.

Further, since the continuous operation step is performed when the dissolved ozone concentration of the ozone water is equal to or higher than the threshold value, and the ozone gas supply step is performed when the dissolved ozone concentration of the ozone water is lower than the threshold value, it is possible to suppress a cleaning failure due to ozone water having an insufficient concentration. This is particularly effective when the water quality changes and the dissolved ozone concentration may decrease when ozone water is continuously produced, such as when treated water, the water quality of which is likely to change, is used as the water to be dissolved.

Further, the controller in embodiment 1 switches between the ozone gas supply step and the continuous operation step based on the water quality of the ozone water, more specifically, based on the concentration of dissolved ozone in the ozone water, but the water temperature, pH, and organic matter concentration of the ozone water may be used as the water quality of the ozone water to be used as a criterion for the step switching. In these cases, the water temperature, pH, or organic matter concentration of the ozone water in the ozone water generation unit is also measured, and the ozone gas supply step and the continuous operation step are switched by comparing the measured value with a threshold value. More specifically, the configuration is such that the ozone gas supply step is switched to the continuous operation step when the measured values of the water temperature, the pH value, or the organic matter concentration are less than the threshold values, and the continuous operation step is switched to the ozone gas supply step when the measured values are equal to or greater than the threshold values. This can provide the same effect as in embodiment 1 in which the dissolved ozone concentration is used.

Further, the process may be switched from the ozone gas supply step to the continuous operation step based on the supply time of the ozone gas or the supply amount of the ozone gas. In the case of the ozone gas supply time switching step, a timer is provided in the control unit, and the time elapsed after the start of the ozone gas supply step is regarded as the ozone gas supply time to determine whether the switching step is possible. In the case of switching the process based on the supply amount of the ozone gas, an arithmetic unit for calculating the supply amount of the ozone gas is provided in the control section, and whether or not to switch the process is determined based on the calculation result. When the ozone gas supply amount is used, the following configuration is also considered: the amount of ozone gas supplied is measured in the ozone gas supply unit or the ozone gas supply pipe, and the measurement result is sent to the control unit.

The ozone water generator may be provided with a water quality adjuster for adjusting water quality such as water temperature, pH, and organic matter concentration. By actively adjusting the water quality by the water quality adjusting portion, it is possible to prevent a decrease in the dissolution efficiency of the ozone gas and a cleaning failure of the separation membrane, and to further improve the cleaning effect.

Further, the supply start timing of the dissolved water at the start of the continuous operation step and the supply start timing of the ozonated water may be the same, or the supply of the dissolved water may be started when the water level in the ozonated water generation unit becomes equal to or lower than a certain level by starting the supply of the ozonated water first.

Embodiment mode 2

Next, embodiment 2 will be described with reference to fig. 4A and 4B. The same or equivalent portions as those in fig. 1A to 3 are denoted by the same reference numerals, and the description thereof is omitted. Embodiment 2 is different from embodiment 1 in that a plurality of ozone water generation units are provided. Fig. 4A and 4B are structural diagrams showing a membrane separation activated sludge system and a membrane cleaning apparatus in embodiment 2, fig. 4A being a diagram illustrating an ozone gas supply step, and fig. 4B being a diagram illustrating a continuous operation step. The dissolved water supply step is the same as that in embodiment 1 except for the case described below, and therefore, illustration thereof is omitted. As shown in fig. 4A, the membrane separation activated sludge system 200 includes a membrane separation activated sludge apparatus 20 and a membrane cleaning apparatus 401, the membrane separation activated sludge apparatus 20 includes a membrane separation tank 1 and a separation membrane 2, and the membrane cleaning apparatus 401 cleans the separation membrane 2.

The membrane cleaning device 401 is a cleaning device for cleaning the separation membrane 2. The membrane cleaning device 401 includes: a dissolved water supply unit 8 for supplying the dissolved water to the 1 st ozone water generation unit 91; a 1 st ozone water generator 91 and a 2 nd ozone water generator 92 for generating ozone water by dissolving ozone gas in dissolved water; an ozone gas supply part 10 for supplying ozone gas to the 2 nd ozone water generation part 92; an ozone water supply part 11 for injecting the ozone water generated in the 2 nd ozone water generation part 92 into the inside of the separation membrane 2; and a control unit 12 for switching the operations of the dissolved water supply unit 8, the ozone gas supply unit 10, and the ozonated water feed unit 11 in accordance with the process. The 2 nd ozone water generator 92 is provided with a dissolved ozone sensor 9b for measuring the dissolved ozone concentration of the ozone water in the 2 nd ozone water generator 92, and the controller 12 is connected to the dissolved ozone sensor 9b via a signal line 51.

The dissolved water supply unit 8 is connected to the 1 st ozone water generation unit 91 via the dissolved water supply pipe 3 c. The dissolved water is dissolved by the ozone gas in the 1 st ozone water generation part 91 and the 2 nd ozone water generation part 92 to become ozone water, and the dissolved water is supplied from the dissolved water supply part 8 to the 1 st ozone water generation part 91 through the dissolved water supply pipe 3 c.

The 1 st ozonated water generation unit 91 is connected to the 2 nd ozonated water generation unit 92 via the dissolved water supply pipe 3f, and the 2 nd ozonated water generation unit 92 is connected to the ozonated water supply unit 11 via the ozonated water supply pipe 3b 1. The 1 st ozonated water generator 91 and the 2 nd ozonated water generator 92 are configured to be capable of storing liquid therein, and capable of storing dissolved water supplied from the dissolved water supply unit 8 and ozonated water generated from the dissolved water. The dissolved water stored in the 1 st ozonated water generation unit 91 is supplied to the 2 nd ozonated water generation unit 92 through the dissolved water transfer pipe 3 f.

A gas diffusion part 91a and a gas diffusion part 92a are provided at the bottom of the 1 st ozonated water generation part 91 and the bottom of the 2 nd ozonated water generation part 92, respectively. The gas diffusion portion 92a is connected to the ozone gas supply portion 10 via an ozone gas supply pipe 3d, and the ozone gas supplied from the ozone gas supply portion 10 is discharged as bubbles from the gas diffusion portion 92a and injected into the dissolved water in the 2 nd ozonated water generation portion 92. An ozone gas transfer pipe 3g connected to the gas diffusing part 91a of the ozone water generation part 1 91 is connected to an upper part of the ozone water generation part 2, and the ozone gas that is not dissolved in the ozone water generation part 2 is supplied as an undissolved ozone gas to the ozone water generation part 1 91 through the ozone gas transfer pipe 3 g. The undissolved ozone gas supplied through the ozone gas transfer pipe 3g is discharged as bubbles from the gas diffusion portion 91a and injected into the dissolved water in the 1 st ozone water generation portion 91. The ozone gas that is not dissolved in the 1 st ozone water generation part 91 is discharged to the outside of the system through an ozone off-gas pipe 3e provided above the 1 st ozone water generation part 91.

A connection (not shown) between the 1 st ozone water generation part 91 and the dissolved water supply pipe 3c is provided on one side wall of the 1 st ozone water generation part 91, and a connection (not shown) between the 1 st ozone water generation part 91 and the dissolved water supply pipe 3f is provided on the other side wall of the 1 st ozone water generation part 91. Further, the connection part between the 1 st ozone water generation part 91 and the dissolved water supply pipe 3c is provided at a position higher than the connection part between the 1 st ozone water generation part 91 and the dissolved water supply pipe 3 f. Thereby, the water to be dissolved flows in from a high position, the water flow of the water to be dissolved becomes a downward flow, and the gas flow of the ozone gas as an upward flow from the gas diffusing part 91a and the water flow of the water to be dissolved become a convection. In this case, the dissolved water and the ozone gas are in convection contact with each other, and the dissolution efficiency in the 1 st ozone water generation section 91 is improved.

A connection (not shown) between the 2 nd ozone water generator 92 and the dissolved water supply pipe 3f is provided on one side wall of the 2 nd ozone water generator 92, and a connection (not shown) between the 2 nd ozone water generator 92 and the ozone water supply pipe 3b1 is provided on the other side wall of the 2 nd ozone water generator 92. Further, the connection part between the 2 nd ozone water generator 92 and the dissolved water transfer pipe 3f is provided at a position higher than the connection part between the 2 nd ozone water generator 92 and the ozone water transfer pipe 3b 1. Thus, the flow of the dissolved water and the flow of the ozone gas also form a convection in the ozone water generation part 2, and the dissolution efficiency in the ozone water generation part 2 is improved by the convection contact.

In the "dissolved water supply step" in embodiment 2, first, the dissolved water is supplied from the dissolved water supply unit 8 to the 1 st ozone water generator 91, and the dissolved water supplied to the 1 st ozone water generator 91 is supplied to the 2 nd ozone water generator 92. At this time, after a predetermined amount of the dissolved water is stored in the 1 st ozone water generation part 91, the supply of the dissolved water to the 2 nd ozone water generation part 92 may be started. The other steps in the "dissolved water supply step" in embodiment 2 are the same as in the "dissolved water supply step" in embodiment 1.

In the "ozone gas supply step" in embodiment 2, as shown in fig. 4A, supply of the dissolved water from the 1 st ozone water generation part 91 to the 2 nd ozone water generation part 92 is stopped. Further, the ozone gas supplied from the ozone gas supply part 10 is dissolved in the dissolved water in the 2 nd ozone water generation part 92, and the ozone gas that is not dissolved in the 2 nd ozone water generation part 92 is supplied as an undissolved ozone gas to the 1 st ozone water generation part 91, so that the undissolved ozone gas is dissolved in the dissolved water in the 1 st ozone water generation part 91. Thereby, the ozone water is generated in the ozone water generation units 1 and 2 in the ozone

water generation units

91 and 92 in a semi-batch manner. The dissolved water in which the ozone gas is not dissolved in the 1 st ozone water generating part 91 is supplied to the 2 nd ozone water generating part 92 through the dissolved water transfer pipe 3f, and the ozone gas is further dissolved in the 2 nd ozone water generating part 92. The other steps in the "ozone gas supply step" in embodiment 2 are the same as those in the "ozone gas supply step" in embodiment 1.

The "ozone water supply step" in embodiment 2 is a step of supplying the ozone water stored in the 2 nd ozone water generating unit 92 to the separation membrane 2 to clean the separation membrane 2. In addition, as shown in fig. 4B, the "continuous operation step" in embodiment 2 is a step of supplying the dissolved water from the dissolved water supplier 8 to the 1 st ozonated water generator 91 and supplying the ozonated water from the 2 nd ozonated water generator 92, and also supplying the dissolved water from the 1 st ozonated water generator 91 to the 2 nd ozonated water generator 92. In addition, as in the case of the ozone gas supply step described above, ozone gas is dissolved in the dissolved water in the 1 st ozone water generation part 91 and the 2 nd ozone water generation part 92. Thereby, the continuous production of ozone water is performed in the 1 st ozone water producing unit 91 and the 2 nd ozone water producing unit 92. The other steps in the "continuous operation step" in embodiment 2 are the same as those in the "continuous operation step" in embodiment 1.

In embodiment 2, two ozone water generation parts are provided, but 3 or more ozone water generation parts may be provided. The ozone gas that is not dissolved in a certain ozone water generation part may be supplied as an undissolved ozone gas to another ozone water generation part, and the undissolved ozone gas may be injected into the dissolved water stored in the other ozone water generation part. Further, the undissolved ozone gas that has not been dissolved in the other ozone water generation part may be further supplied to the other ozone water generation part.

In embodiment 2, the same effects as those in embodiment 1 can be obtained.

Further, a plurality of ozone water generating parts are provided, and an ozone gas transfer pipe for transferring the ozone gas that is not dissolved in one ozone water generating part to another ozone water generating part as an undissolved ozone gas is provided. Thus, the ozone gas that has not been dissolved in one ozone water generation part can be re-dissolved in another ozone water generation part without being discharged as an ozone off-gas, and therefore, the dissolution efficiency of the ozone gas can be further improved.

While various exemplary embodiments and examples have been proposed in the present application, the various features, aspects, and functions described in 1 or more embodiments are not limited to the application to a specific embodiment, and can be applied to the embodiments alone or in various combinations.

Therefore, numerous modifications, which are not illustrated, can be conceived within the technical scope disclosed in the present application. For example, the case where at least 1 component is modified, added, or omitted, and the case where at least 1 component is extracted and combined with the components of the other embodiments are also included.

Description of the reference numerals

1. A membrane separation tank; 2. a separation membrane; 3b1, 3b2, an ozone water pipe; 3c, a dissolved water supply pipe; 3d, an ozone gas supply pipe; 3f, a dissolved water delivery pipe; 3g ozone gas transfer piping; 8. a supply part of the dissolved water; 9. an ozone water generating part; 9b, a dissolved ozone sensor; 91. 1 st ozone water generating part; 92. a 2 nd ozone water generating part; 10. an ozone gas supply unit; 11. an ozone water delivery part; 12. a control unit; 13. an ozone concentration receiving section; 14. a storage unit; 15. a determination unit; 20. a membrane separation activated sludge device; 40. 401, a membrane cleaning device; 100. 200 and a membrane separation activated sludge system.

Claims

1. A membrane cleaning apparatus for cleaning a separation membrane for separating contaminated substances contained in water to be treated from the water to be treated by using ozone water stored in an ozone water generation unit,

the membrane cleaning device is provided with:

an ozone gas supply unit configured to supply ozone gas to the ozone water generation unit;

a dissolved water supply unit for supplying the dissolved water to the ozone water generation unit, using water introduced from the outside or treated water treated by the separation membrane as dissolved water;

an ozone water supply unit configured to supply the ozone water stored in the ozone water generation unit to the separation membrane; and

a control unit which performs the following control: while the ozone gas supply part is supplying the ozone gas from the ozone gas supply part to the ozonated water generation part, the dissolved water supply part is supplied with the dissolved water from the dissolved water supply part to the ozonated water generation part, and the ozonated water feed part is fed with the ozonated water from the ozonated water generation part to the separation membrane,

the control unit includes an ozone concentration acquisition unit that acquires a dissolved ozone concentration of the ozone water, a storage unit that stores a predetermined 1 st threshold value and a predetermined 2 nd threshold value, and a determination unit that determines whether or not the dissolved water and the ozone water can be transported,

the determination unit, when the dissolved ozone concentration is equal to or higher than the predetermined 1 st threshold, causes the ozone gas supply unit to supply the ozone gas from the ozone gas supply unit to the ozonated water generation unit, causes the dissolved water supply unit to supply the dissolved water from the dissolved water supply unit to the ozonated water generation unit, and causes the ozonated water feed unit to feed the ozonated water from the ozonated water generation unit to the separation membrane,

and the determination unit stops the supply of the dissolved water from the dissolved water supply unit to the ozonated water generation unit and stops the delivery of the ozonated water from the ozonated water generation unit to the separation membrane when the dissolved ozone concentration is less than the predetermined 2 nd threshold value,

in the step of generating ozone water by supplying the ozone gas from the ozone gas supply unit to the ozone water generation unit in a state where supply of the dissolved water from the dissolved water supply unit to the ozone water generation unit and conveyance of the ozone water from the ozone water generation unit to the separation membrane are stopped, the determination unit determines whether or not the dissolved ozone concentration is equal to or higher than the predetermined 1 st threshold value,

in the step of causing the dissolved water supply unit to supply the dissolved water from the dissolved water supply unit to the ozonated water generation unit and causing the ozonated water feed unit to transfer the ozonated water from the ozonated water generation unit to the separation membrane in a state where the ozone gas supply unit is caused to supply the ozone gas from the ozone gas supply unit to the ozonated water generation unit, the determination unit determines whether or not the dissolved ozone concentration is less than the predetermined 2 nd threshold.

2. The membrane cleaning device according to claim 1,

the ozone water generation unit includes a 1 st ozone water generation unit connected to the dissolved water supply unit, a 2 nd ozone water generation unit connected to the ozone gas supply unit and the ozone water delivery unit, an ozone gas transfer pipe for transferring ozone gas that is not dissolved in the 2 nd ozone water generation unit to the 1 st ozone water generation unit as undissolved ozone gas, and a dissolved water delivery pipe for delivering dissolved water from the 1 st ozone water generation unit to the 2 nd ozone water generation unit,

the undissolved ozone gas is dissolved in the dissolved water in the 1 st ozonated water generation part, and the dissolved water in which the undissolved ozone gas is dissolved is sent from the 1 st ozonated water generation part to the 2 nd ozonated water generation part.

3. The membrane cleaning device according to claim 1 or 2,

the predetermined 1 st threshold value and the predetermined 2 nd threshold value are different values.

4. A membrane cleaning apparatus for cleaning a separation membrane for separating contaminated substances contained in water to be treated from the water to be treated by using ozone water stored in an ozone water generation unit,

the membrane cleaning device is provided with:

an ozonated water supply unit configured to supply the ozonated water stored in the ozonated water generation unit to the separation membrane; and

a control unit for switching the process to be performed,

the control unit is a control unit that switches between an ozone gas supply step of supplying ozone gas to the ozone water generation unit in a state where supply of the dissolved water to the ozone water generation unit and conveyance of the ozone water from the ozone water generation unit to the separation membrane are stopped, and a continuous operation step of supplying ozone gas to the ozone water generation unit, supplying the dissolved water to the ozone water generation unit, and conveying the ozone water to the separation membrane,

the control unit includes an ozone concentration acquisition unit for acquiring a dissolved ozone concentration of the ozone water, and a storage unit for storing a predetermined 1 st threshold value and a predetermined 2 nd threshold value,

when the dissolved ozone concentration of the ozone water in the ozone water supply step is equal to or higher than the predetermined 1 st threshold value, the supply of the ozone water to the separation membrane is started and the step to be performed is switched to the continuous operation step, and when the dissolved ozone concentration of the ozone water in the continuous operation step is lower than the predetermined 2 nd threshold value, the supply of the dissolved water to the ozone water generation unit and the supply of the ozone water to the separation membrane are stopped and the step to be performed is switched to the ozone gas supply step.

5. The membrane cleaning device according to claim 4,

6. A membrane separation activated sludge system comprising a membrane separation activated sludge device and a membrane cleaning device, wherein the membrane separation activated sludge device comprises a membrane separation tank and a separation membrane disposed inside the membrane separation tank, and is configured to obtain treated water by passing treated water containing fouling substances through the separation membrane in a filtration direction and removing the fouling substances from the treated water, and the membrane cleaning device cleans the separation membrane with ozone water stored in an ozone water generation unit,

the membrane cleaning device is provided with:

a control unit which performs the following control: wherein the ozone gas supply unit is configured to supply the ozone gas from the ozone gas supply unit to the ozone water generation unit, and the dissolved water supply unit is configured to supply the dissolved water from the dissolved water supply unit to the ozone water generation unit, and the ozone water supply unit is configured to supply the ozone water from the ozone water generation unit to the separation membrane,

in the step of generating ozone water by supplying the ozone gas from the ozone gas supply part to the ozone water generation part while stopping the supply of the dissolved water from the dissolved water supply part to the ozone water generation part and the conveyance of the ozone water from the ozone water generation part to the separation membrane, the determination part determines whether or not the dissolved ozone concentration is equal to or higher than the predetermined 1 st threshold,

7. A membrane cleaning method for cleaning a separation membrane for separating contaminated substances contained in water to be treated from the water to be treated by using ozone water stored in an ozone water generation unit,

the membrane cleaning method comprises an ozone gas supply step, a dissolved water supply step, an ozone water supply step, and a continuous operation step,

in the ozone gas supply step, ozone gas is supplied to the ozone water generation part in a state where supply of the dissolved water to the ozone water generation part and conveyance of the ozone water from the ozone water generation part to the separation membrane are stopped,

in the dissolved water supply step, the dissolved water is supplied to the ozone water generator by using water introduced from the outside or treated water treated by the separation membrane as the dissolved water,

in the ozone water supply step, the ozone water stored in the ozone water generation unit is supplied to the separation membrane,

in the continuous operation step, the dissolved water supply step and the ozone water supply step are performed while supplying the ozone gas to the ozone water generation unit,

when the dissolved ozone concentration of the ozone water has reached a predetermined 1 st threshold or more during the ozone gas supply step, the ozone water supply step is started to switch the step to be performed to the continuous operation step, and when the dissolved ozone concentration of the ozone water is less than a predetermined 2 nd threshold during the continuous operation step, the supply of the dissolved water to the ozone water generation unit and the supply of the ozone water to the separation membrane are stopped, and the step to be performed is switched to the ozone gas supply step.

8. The membrane cleaning method according to claim 7,

the ozone water generator includes a 1 st ozone water generator to which the dissolved water is supplied and a 2 nd ozone water generator to which the ozone gas is supplied,

the ozone gas undissolved in the ozone water generation part 2 is transferred as undissolved ozone gas to the ozone water generation part 1, the undissolved ozone gas is dissolved in the dissolved water in the ozone water generation part 1, and the dissolved water in which the undissolved ozone gas is dissolved is transported from the ozone water generation part 1 to the ozone water generation part 2.

9. The membrane cleaning method according to claim 7 or 8,